1. Field of the Invention
The present invention relates to a small solenoid valve to be used in various types of analysis and testing equipment, etc., for opening and closing or switching flow paths of a medical liquid, a sample liquid, etc., and specifically, to a small solenoid valve that can be further downsized to realize lower power consumption.
2. Description of Related Art
In blood analysis equipment, water quality analysis equipment, and exhaust gas testing equipment, normally, solenoid-driven diaphragm valves are used as small solenoid valves for opening and closing or switching flow paths of a medical liquid, a sample liquid, etc.
This type of solenoid valve that opens and closes a flow path of a medical liquid, a sample liquid, or the like, has been known by JP2009-257438 A. In this solenoid valve, a highly chemical resistant material is used for liquid contact portions such as a valve chamber and a valve body in order to minimize the effect on the medical liquid or the like, and a diaphragm valve is arranged in order to prevent the medical liquid or sample liquid from flowing into the side of a solenoid chamber, which provides a structure in which the valve chamber is isolated from the solenoid chamber side by the diaphragm.
However, because this conventional type of diaphragm solenoid valve has a large pressure receiving area in the diaphragm because of the structure of the diaphragm, when a liquid pressure in the valve chamber or a liquid pressure from the side of a port is applied to the diaphragm, the diaphragm valve body in a non-biased state may move against a spring force to maintain that state, so that there is a possibility that the valve may unexpectedly open or close.
Therefore, in the solenoid valve using a diaphragm valve having a large pressure receiving area, it is necessary for maintaining the non-biased state to provide a strong spring force of a coil spring or the like to press the diaphragm valve to an opening or closing side.
Also, the coil spring or the like is thereby increased in size, and a solenoid serving as a drive source of the solenoid valve cannot help but be increased in size to make the diaphragm valve actuate against the spring force for maintaining a non-biased state, in which there has been a problem that downsizing of the solenoid valve is hindered.